Stock feeder

ABSTRACT

A strip of metal is intermittently advanced into a metal forming or punching machine by a reciprocating gripper which moves in simple harmonic motion between predetermined limits in response to uniform movement of an actuating member operated by a reciprocating press member. The limits of movement of the gripper can be precisely adjusted without changing the sinusoidal movement of the gripper.

ted States Patent inventor Arthur F. Leis c/o A. F. Leis Co., Inc., 4316 Webster St., Dayton, Ohio 45414 Appl. No. 814,281 Filed Apr. 8, 1969 Patented Aug. 10, 1971 STOCK FEEDER M Claims, 14 Drawing Figs.

US. Cl 72/419, 226/ Ml 11m. Ci. ..B2ld 43/10, B65h 17/26 Field of Search 72/422, 419; 226/141 [5 6] References Cited UNITED STATES PATENTS 1,407,699 2/1922 Marian 226/141 2,250,530 7/1941 Hafecost. 226/141 2,728,572 12/1955 Clark 226/141 Primary Examiner-Richard J. Herbst Assistant Examiner- Robert M. Rogers Attorney-Marechal, Biebel, French & Bugg Patented Aug. 10, 1971 3 Shasta-Sheet 1 FIG -1 99 FTB INVENTOR ARTHUR F. LEIS w, Mvfi ATTORNEYS SLOW FAST

l SLOW Patented Aug. 10, 1971 3 Sheets-Sheet 5 FIG-H FIG-l3 I34 I27 I24 I25 I00 STOCK FEEDER BACKGROUND OF THE INVENTION Numerous devices have been constructed and sold for the purpose of feeding strip stock into a metal forming press or the like. Many ofthese devices require a complex connection with the operating mechanism of the press and are difficult to adjust and repair when necessary. Other stock feeding devices start and stop abruptly which causes slippage between the stock grippers and the metal stock thereby reducing the accuracy of advancement of the stock.

SUMMARY OF THE INVENTION The present invention is directed to an improved stock feeding device which is adapted to be simply mounted on a metal forming. press or die and provides for precisely advancing a strip of stock into the press. The feeding device may be actuated by uniform movement of a reciprocating press member or by independent hydraulic, pneumatic or electrical drive means and is effective to reciprocate a stock gripping member with simple harmonic movement so that it gradually accelerates from the beginning ofits stroke to a maximum speed and then decelerates through the last portion of the stroke to eliminate abrupt movement of the stock and obtain precise feeding of the stock. Both coarse and fine adjustments are provided for changing the length of the stroke and the limits of the stroke without changing the simple harmonic motion so that a precise feed distance may be selected.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the stock feeder constructed in accordance with the invention and illustrating its installation on a press;

FIG. 2 is a side elevational view of the stock feeder shown in FIG. 1;

FIG. 3 is a view looking from left to right along the line 3-3 of FIG. 2; r

FIG. 4 is a sectional view taken generally on the line 4-4 of FIG. 1;

FIG. 5 is a section taken generally on the line 5-5 of FIG. 1 andshowing the feeding mechanism in an advanced position;

FIG. 6 is a section similar to FIG. 5 showing the feeding mechanism in a retracted position;

FIG. 7 is a section taken generally on theline 7-7 of FIG. 1;

FIG. 8 is a section taken generally on the line 8-8 of FIG. 5;

FIG. 9 is an enlarged fragmentary view of a precision stop device for the feeding mechanism;

FIG. 10 is a section taken generally on the line 10-10 FIG. 8;

FIG. 11 is a plan view of another embodiment of the invention;

FIG. 12 is a side elevational view of the embodiment shown in FIG. 11;

FIG. 13 is a section taken generally on the line 13-13 of FIG. 12; and

FIG 14 is a fragmentary section taken generally on the line 14-l4ofFIG.13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2,.the stock feeder incorporates a frame or housing 10 which is mounted in a cantilever manner on the step or shoulder 11 of the lower die show 12 by a series ofscrews 13. In general, the stock feeder includes an actuating mechanism or actuator 14 and a linkage assembly 15 for transferring the motion of the actuator to a movable stock gripper 16 relative to a fixed gripper 17.

The actuator 14 includes an elongated cylinder 20 formed as part of the housing 10 and receiving a reciprocating piston 21 in the form of an elongated tubular member having a cam roller 22 mounted within a recess 24 (FIG. 4) on the left-hand end thereof. A cylinder heat 25 is mounted on the right-hand end (FIG. 4) of the cylinder 20 and supports an inwardly extending pin 26 which positions the right-hand end of an elongated coil spring 27. The spring extends centrally through the cylinder 20 to engage the inner end of a bore 29 within the piston 21 to urge the piston to the left, as shown in FIG. 4. Movement of the piston 21 is effected by the downward uniform movement of a cam member 30 mounted on the upper die show 31 (FIG. 2) of the press. The cam member 30 has a tapered surface 33 which engages the cam roller 22 on the end of the piston 21 to force the piston to the right (FIG. 4) against the bias of the spring 27.

A laterally extending actuator shaft 35 (FIG. 8) is rotatably supported within the housing 10 by bearings 36 and 37. A pinion or gear 38 (FIGS. 4 and 8) is formed on the central portion of the shaft 35 and engages the complementary teeth of a rack 40 formed on the bottom portion of the piston 21 so that the reciprocal motion of the piston 21 is converted to rotary motion on the shaft 35.

Rotation of the shaft 35 is limited in a counterclockwise direction (FIG. 4) by the micrometer stop assembly 42 (FIG. 9) which includes a lever 43 secured to a threaded end portion 44 of the shaft 35 by a nut 45. The end portion 44 of the shaft has a square shoulder which is received in a complementary opening in the lever 44 so that there is no relative motion between the lever 43 and the shaft 35 once they are secured together. The lever 43 has a precision stop surface 46 which is adapted to engage the lower end of an adjustment screw 48 extending through a tapped hole within a projection 49 on the adjacent side of the housing 12. A lock nut 50 is provided on the upper portion of the screw 48 to secure the screw in position once a predetermined adjustment has been made.

A lever support bracket 52 (FIG. 8) is formed integrally on the left-hand end of the shaft 35 and includes a bottom portion 54 which is located eccentric of the shaft 35 (FIG. 5). The bracket 52 carries a slidable adjustment link 55 which has a dovetail or spline connection 56 (FIG. 8) with the bracket 52 and is retained in place by a plate 57 secured to the bracket 52 by a plurality of screws 58. The relative positions between the adjustment link 55 and the bracket 52 is varied by a micrometer adjustment screw 60 (FIG. 10) which has a threaded end portion engaging a threaded hole 62 in the bracket 52. The head of the screw 60 has circumferential groove which receives a projection 64 of the link 55 so that rotation of the screw 60 moves the adjustment link 55 relative to the bracket 52.

A slot is formed within the adjustment link 55 and receives the left-hand end (FIG. 5) of a lever 67. A pivot pin 68 extends through one of three adjustment holes 69 in the link 55 and through an opening within the left-hand end of the lever 67 to connect the lever to the link. The pin 68 is held in position by a retainer plate 70 (FIG. 8) secured to the side of the link 55 by screws 71. To effect coarse adjustment between the lever 67 and the bracket 52, the retainer plate 70 is removed and the pin 68 is removed from one hole 69 and reinserted in another hole 69 in the link 55.

The reciprocable stock gripper 16 is connected to the right end (FIG. 1) of the lever 67 by a pin 72 which extends through upstanding cars 74 of a housing block 75. The housing block 75 is supported for reciprocable movement between front and rear portions 78 and 79 of the housing 10 by a pair of parallel spaced rods 80 which are secured to the front and rear por tions 78 and 79 of the housing. The top surface 82 of the housing block 75 is coplanar or flush with the top surfaces 83 and 84 of the front and rear portions 78 and 79 of the housing to guide a strip of metal stock S (FIG. 2) into the press.

The stock gripper 16 includes a head 85 which extends upwardly from the block 75 on one side of the metal stock. The head 85 has a portion 86 which projects over the metal stock S and forms a flat vertical surface 87. A screw 88 extends horizontally from the lower end of the portion 86 in the direction of advancement of the metal stockS, and a washer 90 and a nut 91 are mounted on the screw 88 for retaining a coil spring 93 which surrounds the screw 88. A gripper plate 94 is mounted on the screw 88 between the coil spring and the surface 87, and the upper end of the gripper plate is engaged by the lower end of a screw 98 which extends through the arm 86 to provide for adjusting the plate 94 within limits in a vertical direction to accommodate metal strips of different thickness. A lock nut 99 holds the adjustment screw 98 precisely in position once it is properly set. The spring 93 urges the lower end of the plate 94 against the metal strip S and holds the strip against the top surface 82 of the gripper block 75 so that the stock moves forwardly with the gripper block 75.

The stationary gripper assembly 17 is mounted on the rear portion 79 of the housing 10 and is constructed substantially identically to the gripper assembly 16 described above. It is therefore given identical reference characters with the subscript (1, h, c etc. The gripper assembly 17 serves as a positive stop to prevent rearward movement of the stock S when the forward gripper assembly 16 is moving to the right, as viewed in FIG. 2.

In operation of the invention, the stock feeder is mounted on the lower die show 12 or equivalent portion of a metal forming machine. This may be quickly performed since only the forward portion of the feeder is required to be secured to the machine. Moreover, the compact stock feeder requires little space adjacent the machine. The actuator cam 30 is adjusted to engage the roller 22, and the stock S is placed along the flat surfaces of the block 75 and the housing portions 78 and 79. The stock grippers 16 and 17 are adjusted to grip securely the stock S during their operation.

In accordance with the desired length of advancement or feed of the stock, the pin 68 is inserted into one set of holes 69 within the link 55 and through the corresponding hole within the lever 67. The different holes 69 provide for changing the distance between the axes of the shaft 38 and the pin 68 and thereby changing the length of the feed in incremental steps. Adjustment of the screw 60 provides for fine adjustment of the stroke of the gripper 16. The micrometer adjustment 42 (FIG. 9) which controls the clockwise limit of rotation of the shaft 35, is adjusted by loosening the lock nut 50 and turning the screw 48 with an appropriate tool. Since a full turn of the screw 48 causes only a few thousands adjustment in the forward limit oftravel of the stock gripper l6, precision advancement of the stock is easily and quickly accomplished.

Once the forming press is in operation and the top die shoe 31 and the cam 30 are reciprocating, the stock S is automatically fed into the forming apparatus in the following manner. The tapered cam surface 33 engages the roller 22 forcing the piston 21 to the right, as viewed in FIG. 4, against the bias of the spring 27. This action causes the shaft 35 to rotate in a clockwise direction (FIG. 4) thereby rotating the bracket 52 in a clockwise direction and causing the lever 67 to move upwardly and to the right, as viewed in FIGS. and 6, thereby shifting the block 75 of the gripper 16 away from the press. As the gripper 16 moves to the right (FIG. 1), the gripper plate 94 slides along the top surface of the metal stock and no gripping action is present. Should the metal stock S tend to slide with the gripper 16, the backup gripper 17 on the rear portion 79 of the housing immediately blocks this action by wedging the stock S firmly against the top surface 84 of the rear portion 79.

Once the upper die shoe or punch holder reaches its bottom position and commences to move upwardly, the cam 30 allows the piston 21 to move forwardly under the bias of the spring 27. This action reverses the direction of rotation of the shaft 35 so that the bracket 52 and the adjustment link 55 are rotated in a counterclockwise direction from the position shown in FIG. 6 to that shown in FIG. 5. Because the pin 68 is substantially in the same horizontal plane as the axis of the shaft 35, the initial movement of the gripper 16 is quite slow as the pin 68 moves through its semicircular are, as shown in FIG. 6. As the pin 68 moves further along this arc, the horizontal component of this motion increases until the pin 68 reaches a point directly above the axis of the shaft 35 where the horizontal component of the speed is at a maximum. Thereafter, the gripper l6 commences to slow down until it completely stops when it reaches the position shown in FIG. 5 wherein the pin 68 is in the same horizontal plane with the axis of the shaft. This simple harmonic motion thus eliminates any abrupt movements of the gripper 16 or the stockS thereby eliminating the possibility of slippage of the stock relative to the stock feeder so that precise feeding is accomplished.

Another embodiment of the invention is shown in FIGS. 11-14. In this embodiment, the stock feeder includes a housing which is adapted to be mounted cantileveredly on the shoulder of a press in the same manner as the embodiment shown in FIGS. 110. The stock feeder further includes an elongated actuator lever 102 pivotally supported by a pin 103 extending horizontally through upwardly projecting ears 104 (FIG. 12) on the right-hand end of the housing 100. The lever 102 includes a downwardly extending actuator portion 105 which is adjustably mounted on the lever and has an upwardly tapered cam surface 106 extending from an inverted U-shaped slot 107. A screw 108 provides for adjusting the position ofthe actuator portion 105 on the lever 102.

The opposite end portion of the lever 102 carries an adjustable stop screw 109 which limits the upward or clockwise movement of the lever 102 by contact with the housing 100. A coil tension spring 112 connects a pin 114 within the rearward end portion of the actuator lever to a shaft 116 (FIG. 11). The lever is pivoted downwardly against the bias of the spring 112 when an arm or member 117 mounted on the supper portion of the die show engages a projection 118 secured to the lever 102 during the downward movement of the die show. A leaf spring 119 assists the tension spring 112 to assure that the lever 102 returns to its upper position.

A rack 120 is supported for reciprocation within the housing 100 below the lever 102, and a roller 121 is mounted on the shaft 116 in position to engage the cam surface 106 and be received within the slot 107 of the actuator lever 102. Normally, the spring 112 urges the rack 120 toward the right (FIG. 12) so that the lever 102 and roller 121 are positioned as shown in broken lines in FIG. 12. However, when the lever 102 is forced downwardly, the cam surface 106 engages the roller 121 causing the roller and the rack 120 to shift toward the left as the roller proceeds along the cam surface and into the slot 107.

The rack 120 has teeth 123 on the bottom thereof for engaging a gear 124 on an actuator shaft 125 journaled in the housing 100 by bearings 126 and 127 to rotate in the same manner as the actuator shaft 35 of the FIGS. 110 embodiment. Thus reciprocation of the rack 120 is converted to rotary motion of the shaft 125 which is retained on one end by a nut 128. A bracket 130 is secured to the other end of the shaft 125 and includes a slotted lower portion 132 which supports a slidable adjustment link 133 (FIG. 13). The link 133 is adjusted by turning a screw 134 (FIG. 14) which extends through the lower portion 132 of the bracket 130 aid is threaded into a downwardly projecting finger 136 of the adjustment link 133. The adjustment link 133 has a U-shaped slot 137 (FIG. 13) which receives an elongated link 138 connected by a pin 139 (FIG. 14) which extends through one ofa plurality ofholes 142 within the link 133.

The other end of the link 138 is connected by a pin 143 (FIG. 11) to a movable stock gripper 16 which is constructed and mounted for reciprocation on rods 80' in substantially the same manner as the stock gripper 16 described above in connection with FIGS. ll0. Similarly the stationary stock gripper 17' is constructed substantially identical to the gripper 17 described above. Accordingly, the stock grippers are given the same reference characters with prime marks and will not be described in detail.

In operation of the embodiment of the invention shown in FIGS. 11-14. the downward uniform movement of the upper die show causes the actuator lever 103 to be forced downwardly so that the cam surface 106 engages the roller 121 forcing the roller and the rack 120 to the left, as viewed in FIG. 12. This movement is transferred to the gear 128 on the shaft 125, causing the shaft 125, the lever support bracket 130 and the adjustment link 133 to rotate through approximately 180.

The pin 139 which connects the links 133 and 138, causes the right-hand end of the link 138 to be raised and moved to the left as thesupport bracket 130 rotates. This action moves the gripper block 16 forwardly so that the gripper forces the metal stock S into the press by a predetermined distance. Because the pin 139 is located in substantially the same horizontal plane as the axis of the shaft 125, initial movement of the gripper 16' is quite slow but gains speed as the pin 139 moves through its semicircular are. As the pin 139 moves further along this are, the horizontal component of the motion increases until the pin reaches the point directly above the axis of the shaft 125 where the horizontal component of the speed is at a maximum. Thereafter, the horizontal speed component of the pin 139 gradually decelerates until the pin 139 is again in substantially the same horizontal plane with the axis of the shaft, although located on the other side ofthis shaft. This simple harmonic motion eliminates any abrupt movements of the gripper 16 or the stock thereby effectively eliminates slippage in the stock feed so that precise feeding is accomplished,

Once the upper die show of the press completes its downward stroke and is raised, the pressure on the actuator lever I02 is removed and the springs 112 and 119 cause the lever to pivot about its support pin 103 to its raised or elevated position shown in broken lines in FIG. 12. This action removes the camming pressure on the roller 121 so that the coil spring 112 moves the rack 120 to the right (FIG. 12) causing the gear 128 to rotate in a clockwise direction whereby bracket 130 is rotated to its initial or starting position. The stock gripper 17' prohibits rearward movement of the metal stock during the return stroke ofthe gripper 16, as described above.

As mentioned above, it is possible to adjust coarsely the stroke of the feeder 16 or 16' by removing the pin 139 and placing it through one of the adjacent holes 142 in the link 133, as shown in FlG. 14. Similarly, fine adjustment of the stroke can be obtained by rotating the screw 134 to move the pivot axis of the pin 139 relative to the axis of the shaft 125. This embodiment thus provides a positive feed of the gripper 16' and the metal stock during a downward uniform movement of the press member, and the gripper 16' is returned by the spring 112.

From the drawings and the above description, it is apparent that a stock pusher constructed in accordance with the invention provides desirable features and advantages. As a primary feature, the stock pusher provides for generally simple harmonic movement of the stock gripper in response to uniform movement of an actuating member. That is, the stock grippergradually accelerates from a stopped position to a maximum speed and then gradually dccelerates to a stopped position thereby eliminating sudden steps of the stock and increasing accuracy of feed. While the feeder is ideally suited for actuation by uniform linear movement of a press member, it may also be actuated by hydraulic, pneumatic or electrical drive means mounted directly thereon.

Another important advantage is provided by the fact that the stock gripper may be quickly' and easily mounted on a press without a complex linkage system connecting the gripper to the press to provide correlated movements therebetween. Furthermore, the feeder has both coarse and fine adjustments for the stroke of the stock gripper. Moreover, the embodiment shown in FIGS. 11-l4 provides for feeding the stock a precise distance regardless of slight lateral movement which may occur within the upper die shoe or press member.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scope and spirit ofthe invention.

What I claim is:

1. A strip stock feeding device for advancing stock into a metal working press at a precise rate comprising, a housing adapted to be mounted on the press or a die shoe, a shaft rotatably supported by said housing, an actuator adapted to be moved in response to linear movement ofa component of the press and effective to rotate said shaft through a predetermined angle, a stock gripper mounted on said housing for reeiprocable movement between predetermined limits to advance the stock into the press, and means connecting said shaft to said gripper to effect a gradual acceleration and deceleration of movement of said stock gripper at said limits in response to rotation of said shaft and uniform movement of said actuator for eliminating abrupt termination of the movement of the stock.

2. A device as defined in claim 1 including means for precisely adjusting the length of stock advanced by said gripper without changing said gradual acceleration and deceleration of movement of said gripper.

3. A device as defined in claim 1 wherein said means for effecting said movement of said stock gripper include a rack supported by said housing for reciprocating movement, means for moving said rack in response to movement of said actuating member, said shaft extending transversely of said rack, a pinion mounted on said shaft and engaging said rack, a bracket mounted on said shaft for rotation with said pinion through an angle of approximately I in response to movement of said rack, and a link connecting said bracket to said gripper.

4. A device as defined in claim 1 including an arm mounted on said shaft for rotation therewith, means forming a stop for said arm, and an adjustable screw cooperating with said stop to provide a precise adjustment of one of said limits of movement of said gripper.

5. A device as defined in claim 1 wherein said connecting means comprise a bracket mounted on said shaft for rotation therewith through an angle of approximately and a link connecting said bracket to said gripper.

6. A device as defined in claim 5 including a block slidably mounted on said bracket and pivotally connected to said link, and a screw adjustably connecting said block to said bracket to provide for precision adjustment of the stroke of said gripper.

7. A device as defined in claim I wherein said actuating member comprises a lever pivotally connected to said housing means forming a cam surface on said lever, and a roller connected to said rack and positioned for engagement by said cam surface to effect said movement of said rack in response to pivotal movement of said lever.

B. A strip stock feeding device for advancing the stock into a metal working press at a precise rate comprising, a housing adapted to be mounted on the press or a die shoe, a shaft rotatably supported by said housing, an actuator adapted to be moved in response to movement of the press and effective to rotate said shaft through a preset angle, bracket means secured to said shaft for rotation therewith, a stock gripper mounted on said housing for reeiprocable movement between predetermined limits to advance said stock into the press, and a link connecting said bracket means to said gripper to effect a gradual acceleration and deceleration of movement of said stock gripper at said limits for eliminating abrupt termination of the movement ofthe stock.

9. A device as defined in claim 8 wherein said actuator comprises a cylinder in said housing, a piston in said cylinder, means for moving said piston in response to movement of the metal working press, and rack means interconnecting said piston and said shaft for rotation of said shaft in response to movement of said piston.

10. A device as defined in claim 8 including an arm rigidly secured to one end of said shaft and extending radially therefrom, a projection on said housing having an internally threaded bore therethrough, and an adjustable screw in said bore and having an end adapted to contact said lever to form one ofsaid limits of movement ofsaid gripper.

11. A device as defined in claim 8 including an adjuster block slidably mounted on said bracket means, and screw means for adjusting the relative position of said adjuster block and said bracket means to vary precisely the length of the stroke of said gripper.

12. A device as defined in claim 11 including a tongue and groove connection between said adjuster block and said bracket means.

13. A device as defined in claim 8 including pin means spaced guide rods mounted on said housing and supporting said gripper for said reciprocable movement. 

1. A strip stock feeding device for advancing stock into a metal working press at a precise rate comprising, a housing adapted to be mounted on the press or a die shoe, a shaft rotatably supported by said housing, an actuator adapted to be moved in response to linear movement of a component of the press and effective to rotate said shaft through a predetermined angle, a stock gripper mounted on said housing for reciprocable movement between predetermined limits to advance the stock into the press, and means connecting said shaft to said gripper to effect a gradual acceleration and deceleration of movement of said stock gripper at said limits in response to rotation of said shaft and uniform movement of said actuator for eliminating abrupt termination of the movement of the stock.
 2. A device as defined in claim 1 including means for precisely adjusting the length of stock advanced by said gripper without changing said gradual acceleration and deceleration of movement of said gripper.
 3. A device as defined in claim 1 wherein said means for effecting said movement of said stock gripper include a rack supported by said housing for reciprocating movement, means for moving said rack in response to movement of said actuating member, said shaft extending transversely of said rack, a pinion mounted on said shaft and engaging said rack, a bracket mounted on said shaft for rotation with said pinion through an angle of approximately 180* in response to movement of said rack, and a link connecting said bracket to said gripper.
 4. A device as defined in claim 1 including an arm mounted on said shaft for rotation therewith, means forming a stop for said arm, and an adjustable screw cooperating with said stop to provide a precise adjustment of one of said limits of movement of said gripper.
 5. A device as defined in claim 1 wherein said connecting means comprise a bracket mounted on said shaft for rotation therewith through an angle of approximately 180*, and a link connecting said bracket to said gripper.
 6. A device as defined in claim 5 including a block slidably mounted on said bracket and pivotally connected to said link, and a screw adjustably connecting said block to said bracket to provide for precision adjustment of the stroke of said gripper.
 7. A device as defined in claim 1 wherein said actuating member comprises a lever pivotally connected to said housing means forming a cam surface on said lever, and a roller connected to said rack and Positioned for engagement by said cam surface to effect said movement of said rack in response to pivotal movement of said lever.
 8. A strip stock feeding device for advancing stock into a metal working press at a precise rate comprising, a housing adapted to be mounted on the press or a die shoe, a shaft rotatably supported by said housing, an actuator adapted to be moved in response to movement of the press and effective to rotate said shaft through a preset angle, bracket means secured to said shaft for rotation therewith, a stock gripper mounted on said housing for reciprocable movement between predetermined limits to advance said stock into the press, and a link connecting said bracket means to said gripper to effect a gradual acceleration and deceleration of movement of said stock gripper at said limits for eliminating abrupt termination of the movement of the stock.
 9. A device as defined in claim 8 wherein said actuator comprises a cylinder in said housing, a piston in said cylinder, means for moving said piston in response to movement of the metal working press, and rack means interconnecting said piston and said shaft for rotation of said shaft in response to movement of said piston.
 10. A device as defined in claim 8 including an arm rigidly secured to one end of said shaft and extending radially therefrom, a projection on said housing having an internally threaded bore therethrough, and an adjustable screw in said bore and having an end adapted to contact said lever to form one of said limits of movement of said gripper.
 11. A device as defined in claim 8 including an adjuster block slidably mounted on said bracket means, and screw means for adjusting the relative position of said adjuster block and said bracket means to vary precisely the length of the stroke of said gripper.
 12. A device as defined in claim 11 including a tongue and groove connection between said adjuster block and said bracket means.
 13. A device as defined in claim 8 including pin means forming a pivot connection between said link and said bracket means, and means for locating said pin means at spaced intervals on said bracket means to provide coarse adjustment of said limits of movement of said stock gripper.
 14. A device as defined in claim 1 including a set of parallel spaced guide rods mounted on said housing and supporting said gripper for said reciprocable movement. 